So Do Auxillary LED Lights Need A Relay.

[wrooster]

A lot of the small toggle switches are just rated at 6 amps. One just needs to look carefully at the ratings and not work so close to the ratings.

I might take a little issue with the 'most toggle switches can handle 10 amps'. I've replaced too many '10 amp' switches that have failed when being used in circuits drawing 7-8 amps. Cheap switches perhaps. Relays are really the best way to go.

That rating is the steady state current rating.

With incandescent lamps and certain types of capacitive loads (incl. HID ballasts, buck-mode LED drivers, etc), the inrush (startup) current is far, far higher than the steady state current. Hence, every time you open or close the switch contacts, the mating surfaces get more and more pitted as material is transferred from one contact to another. This effect in turn reduces the contact area, so the next time the switch is actuated the current density (A/mm^3) is even higher and further pitting/erosion occurs. Lather, rinse, repeat -- and eventually the contacts fail.

For this reason, some types of high current relays are far more reliable than typical switches, because the relay contacts can be specifically designed for high inrush applications. Some ways of doing so include mercury "wet contacts" and long wiping engagement action. These sorts of approaches are used for motor contactors, which face a long, hard life of high inrush.

wrooster

 

[k0ua]

That rating is the steady state current rating.

With incandescent lamps and certain types of capacitive loads (incl. HID ballasts, buck-mode LED drivers, etc), the inrush (startup) current is far, far higher than the steady state current. Hence, every time you open or close the switch contacts, the mating surfaces get more and more pitted as material is transferred from one contact to another. This effect in turn reduces the contact area, so the next time the switch is actuated the current density (A/mm^3) is even higher and further pitting/erosion occurs. Lather, rinse, repeat -- and eventually the contacts fail.

For this reason, some types of high current relays are far more reliable than typical switches, because the relay contacts can be specifically designed for high inrush applications. Some ways of doing so include mercury "wet contacts" and long wiping engagement action. These sorts of approaches are used for motor contactors, which face a long, hard life of high inrush.

wrooster

All true. That is why I said, "don't work so close to the ratings". A 20 amp rated switch that is switching a 2 amp load is likely to last. A 10 amp rated switch that is switching a 7 amp steady state load is liable to fail.

 

[ishiboo]

3x18W? No. But the light bar on my Kioti is 234W which is 20A with the tractor not running.

So, it depends a lot on the application and number of LEDs. If you are replacing existing lights with a comparable output LED, then no you can reuse all the same wiring/etc. as LEDs are way more efficient.

 

[ishiboo]

All true. That is why I said, "don't work so close to the ratings". A 20 amp rated switch that is switching a 2 amp load is likely to last. A 10 amp rated switch that is switching a 7 amp steady state load is liable to fail.

If you use crap switches, sure. A quality 10A switch will be rated to at least tens of thousands of cycles. Contura switches come in a lot of different visual styles, but they are all well-sealed and reliable switches and work great in tractor applications switching loads.

There are many reasons to use relays though.

 

[dragoneggs]

I agree with a relay not being needed for the LEDs you are planning. That said, I did install a relay as it is 'easier' on the switches albeit a little harder to wire. I installed 4 LED lights on 2 switches on my ROPS so I have two facing fwd and two back. I also agree with putting a in line fuse. Here is a link to my install... some nice electrical advice from 4shorts didn't hurt.

http://www.tractorbynet.com/forums/build-yourself/299015-led-light-install-but-look.html

 

[LividTaco]

I usually install them on things I consider "set and forget" like if I want to have side lights come on when I hit my headlights the relay can do that for me. Think of a relay as a question/answer. IF / THEN. There are limitless uses for relays and depending on what you want whatever your powering to do and when will determine the usefulness of one.

 

[ArlyA]

When I add a couple of LED lights, I will not install a relay just for that low draw application. We do add relays but on a different circuit. Same as ishiboo, we've found many switches to be of such poor quality, to be not worth installing them. We found Pollak brand to be well made and last a very long time.

Attached is a couple of photos taken during night operations. The 2nd one is yellowed from the strobe firing.

If you use crap switches, sure. A quality 10A switch will be rated to at least tens of thousands of cycles. Contura switches come in a lot of different visual styles, but they are all well-sealed and reliable switches and work great in tractor applications switching loads.

There are many reasons to use relays though.